Along with radiation, chemotherapy is the mainstay of cancer therapy. However, most of the currently available chemotherapeutic agents often cause side effects, limiting the use of an effective drug dosage. Furthermore, tumor cells often develop resistance to anticancer drugs. These two problems are largely responsible for the failure of current cancer therapy.
Certain quinoline compounds, such as chloroquine, have been demonstrated to kill cells in a cancer-specific manner, although their cell-killing effects are usually low. In addition, certain quinoline compounds have been demonstrated to be useful as sensitizers when used in combination with radiation or other anticancer agents. In other studies, it was demonstrated in vitro and in vivo that certain sulfonyl derivatives possess antitumor activity. Still, the low efficacy of currently available quinoline compounds necessitates the development of more efficient (and still safe) quinoline compounds, for use, e.g. in the treatment of cancer.
Many anticancer agents kill cancer and non-cancer cells equally well. This indiscriminate killing of cancer and normal cells by anticancer drugs may be responsible, at least in part, for the high side effects shown by many anticancer drugs. Therefore, there is a need to develop compounds with high efficacy and low side effects, for example compounds that can kill cells in a cancer-specific manner, and to develop compounds that suppress the development of drug resistance.